Continuous process for production of scrambled eggs

ABSTRACT

The present invention is directed to a process and system for producing scrambled eggs having a homogenous firmness. The process and system maximizes scrambled egg product consistency and minimizes channeling, fouling and equipment wear previously associated with production of scrambled eggs by periodically interrupting the flow of egg through the system of the invention.

FIELD OF THE INVENTION

[0001] This invention is directed to a process and a system for theproduction of scrambled eggs. More particularly, process and the systemof the invention are directed to producing homogeneous scrambled eggswith a homogenous firmness while minimizing channeling and fouling ofholding tubes used to cook the egg product.

BACKGROUND OF THE INVENTION

[0002] Producing scrambled eggs having a homogeneous firmness at highvolumes without channeling or fouling cooking equipment or damagingheating equipment as a result of the fouling has been a problem. Duringthe initial heating of the eggs with a heat exchanger such as a scrapedsurface heat-exchanger, egg has fouled the heat exchanger even to theextent of breaking the heat exchanger blades.

[0003] Holding tubes where liquid egg is held at elevated temperaturesto cook the eggs develop “channeling”. This is where laminar flowdevelops, as egg thickens and/or coagulates at the outer boundaries ofthe holding tube but tends to stay liquid at the center. In thiscircumstance egg, flows faster through the center of the holding tubethan at the outer perimeter, and as a result, develops a center channel.This creates a product which is not evenly cooked. For instance, eggflowing through the center channel tends to be undercooked, resulting ina watery or mushy egg product. At the same time, egg at the outerboundaries of the holding tube tends to be overcooked, resulting in verysmall pieces. The typical approach for minimizing laminar flow andeliminating large distributions of residence time in a hold tube is toinduce turbulent flow. Turbulence is usually induced by creating highflow velocities or by providing mechanical shear (e.g. in a screwextrusion cooker). This is not acceptable in the production of scrambledegg product, however, as the solid and partially coagulated egg is veryshear sensitive, as excessive shear leads to a finely granulated productwith poor mouth feel.

OBJECTS OF THE INVENTION

[0004] It is an object of this invention to provide a continuous processfor making scrambled egg product which is homogeneous in firmness andwhich is evenly cooked.

[0005] It is another object of this invention to provide a process andsystem for making evenly cooked scrambled egg product having ahomogeneous firmness where the process will also minimize the foulingand channeling in the equipment used to cook the egg product.

[0006] These and other objects of the invention will become apparentwith reference to the following summary and description.

SUMMARY

[0007] The present invention is directed to a process for the productionof scrambled egg product and a system for practicing the process of theinvention. The process and system maximizes scrambled egg productconsistency and/or firmness homogeneity and minimizes channeling,fouling and equipment wear previously associated with the production ofscrambled eggs. Maximization of egg product homogeneity and/orconsistency and minimization of channeling and fouling is provided byperiodically interrupting the flow of egg through the system of theinvention. Flow interruption is achieved by stopping and starting theflow of heated liquid egg product in the holding tube effective forproviding a discontinuous flow of heated egg product in the holdingtube. This reduces laminar flow of the heated egg product in the holdingtube compared to a laminar flow of heated egg product which woulddevelop in the holding tube without the stopping and starting.

[0008] With elimination and/or control of egg channeling in holdingtubes where egg is cooked, the process of the invention eliminates orcontrols undercooking of the eggs and mushy texture that results frominsufficient or non-uniform cooking. The process provides scrambled eggproduct that is sufficiently cooked to allow egg protein to coagulateand provide scrambled egg product having a homogeneous firmness of fromabout 20 mm to about 50 mm (as hereinafter defined) as it exits theholding tube where it is cooked. Further, it has been observed thatovercooking of the egg product and/or subjecting the cooked egg productto significant shear results in an unacceptably large quantity of fines(small particles) in the final product. The process described in theinvention avoids the production of these fines by minimizing theopportunity for “thermal shock” (the development of significant thermalgradients), and ensuring that the velocity, and hence residence time, ofegg product in the holding tube is more uniform.

[0009] In accordance with the process of the invention, liquid eggproduct is first heated to a temperature less than a cooking temperaturefor the egg, but the temperature being sufficiently high to prevent heatshock of the liquid egg product and prevent non-uniformity in thescrambled eggs produced by the process and system of the invention. Theinitially heated egg then is further heated to provide a homogeneouslyheated egg product. This additional or further heating brings the egg toa temperature which is effective for cooking the egg product andeffective for causing the heated liquid whole egg product to coagulatewhen the liquid egg product is held in a holding tube downstream fromthe area of the additional heating. This brings the egg product to acooking temperature to provide a cooked egg product with an apparentviscosity greater than about 1500 centipoises as measured with aBrookfield viscometer with a spindle No. 5 and a constant spindle speedof 20 revolutions per minute. After the egg product is brought to acooking temperature it is transported to a holding tube. Thehomogeneously heated egg product is held in the holding tube at thecooking temperature for an amount of time effective for forming a fullycoagulated and cooked egg product. The flow of egg product-in theholding tube is stopped and started to provide a discontinuous flow ofthe homogeneously heated liquid egg product in the holding tube. Thisstopping and starting is effective to significantly reduce the velocitygradient where egg at the center of the tube moves faster than egg atthe outer periphery of the tube; and hence, reduces the range ofresidence times experienced by the cooked egg flowing through theholding tube as compared to the flow pattern that could be expected todevelop in the holding tube with continuous feed. After cooking, thefully coagulated cooked egg product is removed from the holding tube.The process and system of the invention may be used to process and cookliquid whole egg, as well as liquid egg product as defined herein.

[0010] The initial heating of the egg product brings cool egg fromtemperatures such as about 39° F. (or about 4° C.) to a temperature inthe range of from about 130° F. to about 154° F. in about 1 to about 25minutes, preferably about 5 to 25 minutes. This eliminates thermal shockto the egg when brought to cooking temperature, which shock will cause arapid and sudden coagulation of at least some part of the egg. This willultimately cause a non-uniform coagulation and cooking of the eggproduct in the holding tube.

[0011] During the initial heating, the egg product may increase to aviscosity of from 100 cps to about 1500 cps (Brookfield viscometer witha spindle No. 5 and a constant speed of 20 rpm measured at 25° C.). Theinitial heating may be accomplished using any type of heat exchanger asknown in the art for this purpose, such as a tube in tube pre-heater.

[0012] After the initial heating, the initially heated liquid eggproduct is further heated as uniformly as possible to bring the eggproduct to a cooking temperature before it is transported to a holdingtube for cooking. If the egg is brought to temperature with a hotsurface, a significant thermal gradient should not be allowed todevelop. To this end, a scraper can be used to continuously refresh thematerial at the hot surface with cooler material from the bulk of theegg in the heating device. Alternatively, local turbulence may beinduced in the heating device, without causing significant turbulencedownstream, by using pulsed flow through the heat exchanger. The hotliquid egg is much less shear sensitive than the completely or partiallycoagulated material, and so acceptable product can be produced despitethe level of shear induced during heating.

[0013] Uniformity of the heating and avoidance of a large temperaturegradient in the egg product ultimately effects the homogeneity offirmness of the egg product exiting the-holding tube. Hence, themeasures used to minimize thermal gradients during the final heatingstep should be sufficient and effective for providing the egg productexiting the holding tube with a homogeneous firmness in the range offrom about 20 mm to about 50 mm when the egg product also is subjectedto the discontinuous flow as described in this application.

[0014] In one aspect of the invention, steam is injected into the eggproduct to further and homogeneously heat the egg product to a cookingtemperature in the range of about 163° F. to about 175° F. The steamgenerally is injected at a pressure of from about 5 psi to about 40 psi.The steam injection is immediately followed by a shear-inducing stepsuch as, in the preferred embodiment, a pump. The injection of the steamand operation of the downstream mixing device is done in a manner, rateand pressure that is effective for maintaining a homogenous product witha uniform and homogeneous firmness in the range of from about 20 mm toabout 50 mm, preferably about 25 mm to about 45 mm as the egg productexits the holding tube. The steam temperature generally ranges fromabout 240° F. to about 270° F.

[0015] When liquid egg product is transported into the holding tube andthe flow of product through the holding tube is interrupted or stoppedthen started, the product has a residence time in the holding tubeeffective for providing the firmness described above which is generallyabout 8 to about 15 minutes being cooked at a temperature range of about163° F. to about 175° F.

[0016] The process of the invention may be batch or can be continuous,even with one holding tube. A reciprocating pump can provide theinterruption or stoppage of the flow of egg product through a systemwith one holding tube. In a system with one hold tube, a device thatallows a near continuous feed while providing a discontinuous output maybe introduced between the heating and holding parts of the process. Adevice such as a reciprocating pump may be used for this purpose. In animportant aspect, multiple holding tubes may be used to make the processcontinuous with the flow of homogeneously heated egg product in oneholding tube continuing while the flow of egg product in at least oneother tube is stopped. In a preferred aspect, the process and system ofthe invention has two insulated holding tubes. In this aspect of theinvention, the homogeneously heated liquid egg product is transportedinto one of the holding tubes. A flow control regulator or valveswitches the flow of homogeneously heated egg product from a firstholding tube then to a second holding tube and then back to the firsttube at intervals which push product through the tube, but allow productto reside in the tube to cook the egg and provide the egg product with ahomogeneous firmness of at least about 50 mm or keep the egg product inthe tube for the times and temperatures indicated above. Alternatively,product may be pumped through more than two tubes at appropriateintervals to effect discontinuous flow through the tubes.

[0017] After exiting the holding tube(s), fully coagulated or cooked eggproduct may be extruded to form a homogeneous scrambled egg producthaving the firmness in the range of from about 20 mm to about 50 mm. Thescrambled egg product may be immediately frozen and packaged or may bemixed with other food items and then frozen and packaged.

[0018] In another aspect, the invention further provides a continuoussystem for producing scrambled eggs. The system includes a holding tankeffective for providing liquid whole egg product. The liquid whole eggproduct is transported to a heat exchanger which is effective forinitially heating the liquid egg product to a temperature of not morethan about 154° F. and to prevent heat shock of the liquid egg productin subsequent processing steps.

[0019] The system of the present invention may further include a steaminlet effective for providing an injection of steam at a temperature andpressure sufficient to raise the egg product to a temperature at whichcooking can occur, followed by a device to impart significant mixing andincrease in pressure, such as a Silverson Shear pump, effective forensuring that the steam energy is provided homogenously to the eggmixture. The pump provides the environment that insures that the heatfrom the steam is rapidly dispersed within the liquid egg product,thereby avoiding thermal shock. Further, the downstream pump providespart of the backpressure needed to force material through the hold tube,thereby allowing the steam to be introduced at a lower pressure(temperature) than would otherwise be possible. The steam injection andsubsequent pump are operated in a manner effective for evenly heatingthe liquid egg product to a cooking temperature which will cook the eggproduct in the holding tube(s) as described above. In an importantaspect, the steam heated liquid egg product has a temperature in therange of from about 163° F. to about 175° F. The system of-the inventionincludes a means for controlling the flow of steam heated egg product,such as a reciprocating pump or valve, to at least one holding tube, andpreferably at least two holding tubes. Egg product is maintained in theholding tube(s) at a time and temperature effective for forming a fullycoagulated or cooked egg which has a uniform firmness in the range offrom about 20 mm to about 50 mm when it exits the holding tube. Thescrambled egg product from the holding tube then is extruded through anextruder.

DESCRIPTION OF FIGURES

[0020]FIG. 1 illustrates-an aspect of the invention where the processincludes steam injection and two holding tubes.

[0021]FIG. 2 shows an aspect of the invention where the process includessteam injection and one holding tube.

[0022]FIG. 3 illustrates an aspect of the invention where the processincludes heat exchangers and two holding tubes.

[0023]FIG. 4 illustrates an aspect of the invention where the processincludes heat exchangers and one holding tube.

[0024]FIG. 5 illustrates laminar flow.

[0025]FIG. 6 illustrates environmental scanning electron microscopeimage of egg heated with a scraped surface heat exchanger and withdiscontinuous flow through a holding tube.

[0026]FIG. 7 illustrates an environmental scanning electron microscopeimage of egg heated with steam injection and with discontinuous flowthrough a holding tube.

[0027]FIG. 8 illustrates environmental scanning electron microscopeimage of egg heated with a scraped surface heat exchanger and withcontinuous flow through a holding tube.

[0028]FIG. 9 illustrates environmental scanning electron microscopeimage of egg heated by steam injection and with continuous flow througha holding tube.

[0029]FIG. 10 illustrates a front view of an extruder plate.

[0030]FIG. 11 illustrates a front view of an extruder plate.

[0031]FIG. 12 illustrates a front view of an extruder plate.

[0032]FIG. 13 illustrates a front view of an extruder plate.

[0033]FIG. 14 illustrates a side view of an extruder plate.

DETAILED DESCRIPTION

[0034] Definitions

[0035] “Liquid whole egg” means egg white and yolk in the ratio which isgenerally recognized as the ratio of yolk to white in shell eggs. Thatratio generally is in the range of from about 1 part yolk to about 2parts egg white. Liquid whole egg generally has about 23.5 weightpercent solids and 76.5 weight percent water. The liquid whole egg mayinclude other additives such as salt, sugar, nisin, starch and xanthangum.

[0036] As used herein the term “liquid egg product” means a productcomprising from about 8% to about 40% egg yolk and from about 67% toabout 81% egg white which product may include additional additives.

[0037] “Scrambled egg product” is made according to the invention usingliquid egg product.

[0038] “Laminar flow” means a flow of liquid egg in a conduit which isfaster at the center of a conduit, but slower at the outer dimension ofthe conduit as seen in FIG. 5.

[0039] “Homogeneous firmness” throughout the egg product means that atleast about 95 weight percent of cooked egg product exiting the holdingtube has a specified firmness, such as from about 20 mm to about 50 mm.

[0040] One aspect of the present invention is illustrated in FIG. 1. Asshown in the FIG. 1, liquid whole egg or liquid egg product may beprovided to the process in a holding tank 20 which is maintained at atemperature of from about 35° F. to about 45° F. Liquid egg product ispumped via a pump 30 downstream to a heat exchanger 40. Heat exchanger40 may be any type of heat exchanger as known in the art for thispurpose, but a tube in tube heat exchanger is preferred. Examples of thetypes of heat exchangers, which may be used at this point of the processincludes a triple tube heat exchanger, a plate and frame heat exchanger,Roswell heater (tubular exchanger which uses a rectangular shapedannular area between two cylindrical heat transfer surfaces), andelectrical resistance heated tubes.

[0041] In this aspect of the invention, the liquid egg product is heatedto a temperature of about 130° to about 154° F. for about 1 to about 25minutes, preferably from about 140° F. to about 145° F. to provide theinitially heated liquid egg product. The initially heated liquid eggproduct has a viscosity of about 100 cps to about 1500 cps.

[0042] As further shown in FIG. 1, heated liquid egg product is pumpedvia pump 30 downstream of the heat exchanger 40 through check valve 50.Steam is injected into the initially heated liquid egg product at asteam injection site 55 to bring the egg to a cooking temperature. Inthis aspect of the invention, steam is injected at a pressure of about20 to about 40 psi, the steam having a temperature of from about 240° F.to about 270° F. to provide a homogeneous heated liquid egg product. Thesteam used is of food grade and is produced by processes known in theart for this purpose. Steam injection at the indicated pressures is suchthat the subsequent pump provides sufficient mixing of the egg productto effect a homogenous cooked product as it exists the holding tubes.

[0043] In the aspect of the invention shown in FIG. 1, the homogeneousheated egg product is transported via valve 70 downstream to insulatedholding tubes 80. Holding tubes 80 are effective to maintain atemperature of from about 163° F. to about 175° F. for about 8 to about15 minutes to fully cook the egg product which is removed from theholding tube. The egg product has a uniform firmness in the range offrom about 20 mm to about 50 mm. During continuous operation of theprocess, the flow of product into one holding tube 80 occurs while theflow of product into the other holding tube is stopped. The valve 70switches the flow of the egg back and forth between holding tubes 80such that product has a residence time in each holding tube as describedabove. Valves 70 may be any type of valves known in the art for thispurpose, and may be controlled by any type of controllers known in theart for this purpose.

[0044] After exiting holding tube 80, the fully coagulated or cooked eggproduct is extruded at extruder 90. The extruder 90 may include any typeof extruder known in the art for this purpose. Examples of extrudersthat are effective for use with the process of the present inventioninclude those shown in FIGS. 10-14, but the egg product flowingtherefrom will have a uniform firmness of from about 20 mm to about 50mm.

[0045] The extruded egg may be directly frozen and packaged or mixedwith other food products and then frozen and packaged. Examples of otherfood products that can be mixed with the eggs include vegetables, meatproducts, nuts and grains, and mixtures thereof.

[0046] In another aspect of the present invention, egg product istransported to a single holding tube 80 as is shown in FIG. 2. In thisaspect of the invention, the flow of egg is disrupted and/or stopped andstarted by a reciprocating pump 70 to allow product to reside in theholding tube 80 for about 8 to about 15 minutes at the temperaturesdescribed above. The reciprocating pump 70 accepts liquid egg product ona continuous basis, with the barrel of the pump being gradually filledbetween cycles. Material is provided to the holding tubes in the form ofpulses, with each pulse of liquid egg product into the tube displacingan equal volume of material from the product end of the holding tube.

[0047]FIG. 3 illustrates an aspect of the invention where the eggproduct is homogeneously heated with a scraped surface heat exchanger 45which product then is transported to two holding tubes 80, the flowthere being disrupted by valve 70.

[0048]FIG. 4 illustrates an aspect of the invention where egg product ishomogeneously heated in a heat exchanger 45, and then is transported toone holding tube with the flow of egg product being disrupted byreciprocating pump 70.

[0049] The interruption or stoppage and subsequent start of product flowthrough the holding tube 80 is effective for eliminating significantradial velocity gradients in the egg product flowing through the tube.This ensures a uniform, narrowly distributed residence time of theproduct at the cooking temperature, providing a product that ishomogenous in terms of protein and starch structure, firmness andparticle size. The observations about product homogeneity were supportedby lab analysis of the product from various implementation of the systemdescribed herein, as discussed in examples 1-5.

[0050] Lamellar flow, or laminar flow as shown in FIG. 5, occurs where aflow rate of material at the middle 155 of a conduit 150 is higher thanthe flow rate of the materials towards the outside 160 of the-conduit.Laminar flow occurs when materials flow through tubes or conduits withmoderate velocities. A thin layer of material in contact with the tubewall may be stationary, the next layer flows slowly, and the adjacentlayer faster. The material then flows as if it consisted of many thinconcentric cylinders, each moving with a constant velocity whichincreases from the wall toward the center of the tube. The presentinvention minimizes or eliminates laminar flow with the interruption orstoppage and then subsequent start of product flow as described above.

[0051] Extruder plates that may be used in the process of the presentinvention are shown in FIGS. 10-14. The extruder plates are effectivefor providing eggs having a functional piece size similar in appearanceand size to freshly prepared scrambled eggs. Fully cooked scrambled eggsexit the hold tube under a constant steady pressure of about 10 psig toabout 30 psig. The cooked egg is forced through orifices 140 of extruderplate 150 (shown in FIGS. 10-14). The extruder plate 150 may include anumber of designs and orifice sizes as shown in FIGS. 10-14.

[0052] In the extruder plate shown in FIG. 10, the extruder plate 150has a diameter of about 2⅞ inches and the orifices have a diameter ofabout {fraction (35/64)} inches. The center of orifices 140 located onthe outer edge of extruder plate 150 are about 2⅛ inches from the centerof the extruder plate 150. The center of orifices located more to thecenter of the extruder plate are about 1¼ inch from the center of theextruder plate.

[0053] In the extruder plate shown in FIG. 11, the extruder plate 150has a diameter of about 2⅞ inches and includes oblong shaped orifices140. The oblong shaped orifices have a length of about ¾ inch and awidth of about ½ inch. Orifices are spaced apart at least {fraction(11/64)} inches.

[0054] In the extruder plate shown in FIG. 12, the extruder plate 150includes orifices 140 having a diameter of about {fraction (39/64)}inches. The center of these orifices is located about 2 inches from thecenter of the extruder plate.

[0055] In the extruder plate shown in FIG. 13, the extruder plate 150has a diameter of about 3.5625 inches and the orifices 140 have adiameter of about 0.9705 inches. A cross sectional view of the extruderplate along line AA is shown in FIG. 14.

EXAMPLES Example 1 Scraped Surface Heat Exchanger with DiscontinuousFlow

[0056] Liquid whole egg product at a temperature of 40° F. was pumped byuse of a positive displacement pump through a water-jacketed tube intube pre-heater and brought to a temperature of 140° F. The preheatedliquid whole egg product was then pumped by means of a positivedisplacement pump into a scraped surface heat exchanger (SSHE). Thedasher contained within the barrel was operated at 270 rpm. Hot waterwas circulated in the jacket of the SSHE barrel and heat was indirectlytransferred to product contained within the barrel. As the liquid wholeegg product exited the SSHE at a temperature of about 170° F., itimmediately entered one branch of the hold tube. After a period of about5 minutes, a rotating valve opened to a second 100-foot branch of theholding tube and product was forced into this section of the hold tube.The proteins contained within the liquid whole egg product denatured andcoagulation occurred within the hold tube. For a period of 5 minutes theheated liquid whole egg-product was left undisturbed. At the exit of thehold tube, the fully cooked egg was forced through an extrusion plate.The egg pieces were immediately frozen, packaged in bags and the bagswere placed in mastercases. FIG. 6 represents environmental scanningelectron micrograph from samples subjected to the above process.

[0057] Legends in FIGS. 6, 7, 8 and 9 are as follows.

[0058] Acc. V—Accelerating voltage—the voltage used in the electron beam(energy applied).

[0059] Spot—spot size diameter of electron beam in microns.

[0060] Magn—Magnification of the image, in this case 250 times.

[0061] Det—detector used in the imaging system. In this case GSE-GaseousSecondary Electron.

[0062] WD—working distance from the surface of the sample inmillimeters: in these cases 11.5 to 15.0 mm.

[0063] MBar—millibars of water vapor in the electron chamber: in thesecases 3.9 to 4.9 mbar.

[0064] 100 um—is the size of the reference bar on the image.

[0065] IM01-160 is the internal project number.

[0066] A1144 is the internal sample number.

[0067] All samples were frozen.

Example 2 Steam Injection with Discontinuous Flow

[0068] Liquid whole egg product at a temperature of 40° F. was pumpedthrough the use of a positive displacement pump through a water-jacketedtube in tube pre-heater and brought to a temperature of 140° F. Thepre-heated liquid whole egg product was then pumped to the site of steaminjection. Forty pounds of steam was introduced into the stream ofliquid whole egg product. The pre-heated liquid egg product was flowingat a rate of 2300 pounds per minutes. Immediately adjacent to the pointof steam injection, sufficient turbulence was created to incorporate anddisperse steam. The liquid whole egg product, at a temperature of about170° F., immediately entered one branch of the hold tube. After a periodof 5 minutes, a rotating 3-way valve opened so that product flows into asecond branch of the holding tube. The proteins contained within theliquid whole egg product denature and coagulation occurs within the holdtube. For a period of 5 minutes the heated liquid whole egg product wasleft undisturbed. At the exit of the hold tube, the fully cooked egg wasforced through an extrusion plate. The egg pieces were immediatelyfrozen, packaged in bags and the bags were placed in mastercases. FIG. 7represents an environmental scanning electron micrograph from samplessubjected to the above process.

Example 3 Scraped Surface Heat Exchanger with Continuous Flow

[0069] Liquid whole egg product at a temperature of 40° F. was pumpedthrough the use of a positive displacement pump through a water-jacketedtube in tube pre-heater and brought to a temperature of 140° F. Thepreheated liquid whole egg product was then pumped by means of apositive displacement pump into a scraped surface heat exchanger (SSHE).The dasher contained within the barrel was operated at 270 rpm. Hotwater was circulated in the jacket of the SSHE barrel and heat wasindirectly transferred to product contained within the barrel. As theliquid whole egg product exited the SSHE at a temperature of about 170°F., it immediately entered a hold tube. The proteins contained withinthe liquid whole egg product denatured and coagulation occurred withinthe hold tube. At the exit of the hold tube, the fully cooked egg wasforced through an extrusion plate. The egg pieces were immediatelyfrozen, packaged in bags and the bags were placed in mastercases. FIG. 8represents an environmental scanning electron micrograph from samplessubjected to the above process.

Example4 Steam Injection with Continuous Flow

[0070] Liquid whole egg product at a temperature of 40° F. was pumpedthrough the use of a positive displacement pump through a water-jacketedtube in tube pre-heater and brought to a temperature of 140° F. Thepre-heated liquid whole egg product was then pumped to the site of steaminjection. Forty psi of steam was introduced into the stream of liquidwhole egg product. The pre-heated liquid egg product was flowing at arate of 2300 pounds per minutes. Immediately adjacent to the point ofsteam injection, sufficient turbulence was created to incorporate anddisperse steam. The liquid whole egg product, at a temperature of about170° F., immediately entered a hold tube. The proteins contained withinthe liquid whole egg product denatured and coagulation occurred withinthe hold tube. At the exit of the hold tube, the fully cooked egg wasforced through an extrusion plate. The egg pieces were immediatelyfrozen, packaged in bags and the bags were placed in mastercases. FIG. 9represents an environmental scanning electron micrograph from samplessubjected to the above process.

Example 5 Comparison of Cooked Eggs

[0071] Four samples (Examples 1-4) of cooked egg product were evaluatedfor: 1. morphology differences, 2. protein matrix differentiation, and3. degree of starch gelatinization. The samples evaluated were: FIG. 8(Example 3)—scraped surface heat exchanger with continuous flow; FIG. 6(Example 1)—scraped surface heat exchanger (SSHE) with discontinuousflow; FIG. 9 (Example 4)—steam injection with continuous flow; FIG. 7(Example 2)—steam injection with discontinuous flow. These samples weresubjected to environmental scanning electron microscopy, Ramanhyperspectral imaging, and automated polarized light microscopy.

[0072] The general conclusions about morphology are as follows.

[0073] 1. The discontinuous processes produce similar results in termsof morphology;

[0074] 2. The continuous steam injection process produces strikinglydifferent morphology-product than the SSHE continuous process;

[0075] 3. Eggs produced from steam injection with continuous flow (FIG.9, Example 4) had much larger holes in the structure than eggs producedby a SSHE with continuous flow (FIG. 8, Example 3); and

[0076] 4. The core and edges of eggs produced by a SSHE with continuousflow (FIG. 8, Example 3) are very different in structure whereas thecore and edges of eggs produced from steam injection with continuousflow (FIG. 9, Example 4) are more similar.

[0077] In general, the discontinuous process samples are essentiallyhomogeneous with regard to protein.

[0078] The general conclusions about the starch gelatinization are asfollows.

[0079] 1. The continuous flow samples (Examples 3 & 5), and particularlythe continuous flow with steam injection (Example 4), show a morecrystalline starch structure, indicative of non-gelled starch.

[0080] 2. The dicontinuous flow samples (Examples 1 & 2) have noindication of non-gelatinized starch.

[0081] These observations of starch and protein structure demonstratethat, regardless of the heating method used, the distribution ofresidence times caused by operating the holding tube with continuousflow has a significant influence on the product homogeneity, and thatthe use of discontinuous flow to reduce the distribution of residencetimes leads to a more homogenous product. This increased homogeneity hasa significant, positive influence on the acceptability of the finalproduct.

Example 6 Texture Evaluation Test Procedure for Egg Products

[0082] Egg product firmness was measured according to the followingprocedures.

[0083] 1. A standardized cup (16 oz., 473 ml) was filled with productand weighed on a Sauter RP 3000 scale. Total weight was between 380 and460 grams.

[0084] 2. A lid was placed on the cup and the cup was stored in a warmplace until the temperature reached 50° F. to 75° F. The cup withcontents was tapped on a flat surface one time.

[0085] 3. Two leveling screws and a bubble level were used to level apenetrometer (Precision Scientific Petroleum Instruments, Bellwood,Ill.) before each use.

[0086] 4. The combined weight of the cone (102.5 grams) and the test rod(47.5 grams) makes us the required load. Prepared samples were placed inposition on the base of the penetrometer.

[0087] 5. The height of the unit was adjusted so the point of the conewas brought exactly into contact with the surface of the fully cookedegg sample. Coarse and fine adjustment knobs were used.

[0088] 6. Before releasing the thumb release lever, the dial pointer wasset at zero. If not, the “zero adjust nut” was adjusted until the dialpointer was pointing to zero.

[0089] 7. The cone and test rod were released allowing the penetratinginstrument to descend into the sample. The test rod was released bydepressing the thumb release lever and holding the thumb release leverfor 5 seconds.

[0090] 8. The depth gauge rod was gently pushed down as far as it wouldgo. The dial reading indicated the depth of penetration directly intenth of millimeters.

[0091] 9. Values were read and recorded. Dial readings gave penetrationin tenths of millimeters up to 270 point. Hence, on depths greater than38 mm, the dial pointer moves past the zero position. A given value wasadded to 38.0 to determine total depth of penetration.

[0092] 10. The cone was raised and the dial pointer was returned to zeroby depressing the thumb and lift.

[0093] 11. The procedure was repeated with a new sample and averagevalues were recorded.

[0094] 12. Product texture rating as well as extrusion plate holediameter, product number and temperature of the sample was recorded.

[0095] Instrumentation used was Universal Penetrometer Catalog 73510manufactured by Precision Scientific Petroleum Instruments Company 2777Washington Blvd. Bellwood, Ill. 60104.

What is claimed is:
 1. A process for producing scrambled egg productcomprising: first heating a liquid egg product to a temperature lessthan a cooking temperature for the egg, but a temperature which issufficiently high to prevent heat shock of the liquid egg product andprevent non-uniformity in the scrambled eggs produced by the process toprovide an initially heated liquid heated egg product; further heatingthe initially heated liquid egg product to provide a homogeneouslyheated egg, the further heating to a temperature effective for cookingthe egg and effective for causing the heated liquid whole egg product tocoagulate when the liquid egg product is held in a holding tube;transporting the homogeneously heated liquid egg product to a holdingtube; holding the homogeneously heated liquid egg product in the holdingtube for an amount of time effective for forming a fully coagulated egg;stopping and starting a flow of the homogeneously heated liquid eggproduct in the holding tube for providing a discontinuous flow of thehomogeneously heated liquid egg product in the holding tube andeffective to reduce laminar flow of the homogeneously heated liquid eggproduct in the holding tube compared to a laminar flow of thehomogeneously heated liquid egg product which would develop in theholding tube without the stopping and starting; and removing the fullycoagulated egg from the holding tube to form a scrambled egg product. 2.A process as recited in claim 1 wherein the first heating heats theinitially heated liquid egg product to a temperature of from about 130°F. to about 154° F. in about 1 to about 25 minutes.
 3. A process asrecited in claim 1 wherein the initially heated liquid egg product isfurther heated by injecting steam into the initially heated liquid eggproduct.
 4. A process for producing scrambled egg product comprising:first heating a liquid egg product to a temperature of from about 130°F. to about 154° F. to provide an initially heated liquid egg producthaving a viscosity in the range of from about 100 cps to about 1500 cps;injecting steam into the initially heated liquid egg product to providea steam heated liquid egg and to bring the initially heated liquid eggproduct to a temperature effective for causing the initially heated eggproduct to coagulate when the liquid egg product is held in a holdingtube; transporting the steam heated egg product to a holding tube;holding the steam heated egg product in the holding tube for an amountof time effective for forming a cooked egg product having a firmness ofat least about 20 mm; stopping and starting a flow of the steam-heatedliquid egg product in the holding tube, the stopping and startingeffective for providing a discontinuous flow of steam heated egg productin the holding tube and effective to reduce laminar flow of the steamheated egg in the holding tube compared to a laminar flow of steamheated egg which would develop in the holding tube without the stoppingand starting; and removing the cooked egg product to form scrambled eggproduct.
 5. The process as recited in claim 4 wherein the steaminjection heats the steam heated liquid egg product to a temperature offrom about 163° F. to about 175° F.
 6. The process as recited in claims4 or 5 wherein the steam is injected at a pressure of from about 20 toabout 40 psi.
 7. A process for producing scrambled egg productcomprising: first heating a liquid egg product to a temperature of fromabout 130° F. to about 154° F. to provide an initially heated liquid eggproduct having a viscosity of in the range of from about 100 cps toabout 1500 cps; injecting steam into the initially heated liquid eggproduct to provide a steam heated liquid egg and to bring the initiallyheated liquid egg product to a temperature effective for causing theinitially heated egg product to coagulate when the liquid egg product isheld in a holding tube; transporting the steam heated egg product to aholding tube; holding the steam heated egg product in the holding tubefor an amount of time effective for forming a cooked egg product;stopping and starting a flow of the steam heated liquid egg product inthe holding tube, the stopping and starting effective for providing adiscontinuous flow of steam heated egg product in the holding tube andeffective to minimize a radial velocity gradient in the flow of thesteam heated egg in the holding tube compared to a radial velocitygradient of steam heated egg which would develop in the holding tubewithout the stopping and starting; and removing the cooked egg productto form scrambled egg product having a homogeneous firmness throughoutthe egg product in the range of from about 20 mm to about 50 mm.
 8. Aprocess for producing scrambled egg product comprising: heating a liquidegg product to a temperature of from about 130° F. to about 154° F. toprovide an initially heated liquid egg product having a viscosity in therange of from about 100 cps to about 1500 cps; injecting steam into theinitially heated liquid egg product to provide a steam heated eggproduct having a temperature effective for causing the heated eggproduct to coagulate and cook in a holding tube; transporting the steamtreated egg product to at least two holding tubes, holding the steamtreated egg product in the holding tubes for an amount of time effectivefor forming a cooked egg product; alternating the flow of eggs to the atleast two holding tubes to stop and start the flow of the steam treatedegg in the holding tubes effective for providing a discontinuous flow ofsteam treated egg in the holding tube; and removing the cooked eggproduct to form the scrambled egg product.
 9. A process as recited inclaim 8 wherein the scrambled egg product has a homogeneous firmness offrom about 20 mm to about 50 mm.
 10. A system for producing scrambledegg product, the system comprising: a holding tank effective for holdinga liquid egg product at below a temperature of about 50° F.; a heatexchanger effective for heating the liquid egg product from the holdingtank to a temperature in the range of from about 130° F. to about 154°F. to provide an initially heated liquid egg product; a steam injectiondevice effective for injecting steam into the initially heated liquidegg product and providing a steam heated liquid egg product, the steameffective for heating the initially heated-liquid egg product to acooking temperature; at least two holding tubes which receive a flow ofsteam heated liquid egg product; and a valve for controlling the flow ofeggs to the at least two holding tubes, the valve effective for stoppingand starting the flow of steam heated liquid egg product and switchingthe flow of egg product between the at least two holding tubes, the atleast two holding tubes maintaining the steam heated egg product for atime and temperature effective for cooking the steam heated egg product.11. The system as recited in claim 10 wherein the system furtherincludes an extruder downstream from the holding tubes for formingscrambled egg product.
 12. The system as recited in claim 11, whereinthe system provides the scrambled egg product with a homogeneousfirmness of from about 20 mm to about 50 mm.
 13. A scrambled egg productas shown and described in the scanning electron microscope image of FIG.7.
 14. A scrambled egg product as shown and described in the scanningelectron microscope image of FIG.
 6. 15. A process for producingscrambled egg product comprising: first heating a liquid egg product toa temperature less than a cooking temperature for the egg, but atemperature which is sufficiently high to prevent heat shock of theliquid egg product and prevent non-uniformity in the scrambled eggsproduced by the process to provide an initially heated liquid heated eggproduct; further heating the initially heated liquid egg product toprovide a homogeneously heated egg, the further heating to a temperatureeffective for cooking the egg and effective for causing the heatedliquid whole egg product to coagulate when the liquid egg product isheld in a holding tube; transporting the homogeneously heated liquid eggproduct to at least two holding tubes; holding the homogeneously heatedliquid egg product in the holding tubes for an amount of time effectivefor forming a fully coagulated egg; stopping and starting a flow of thehomogeneously heated liquid egg product in the holding tubes forproviding a discontinuous flow of the homogeneously heated liquid eggproduct in the holding tubes and effective to reduce laminar flow of thehomogeneously heated liquid egg product in the holding tubes compared toa laminar flow of the homogeneously heated liquid egg product whichwould develop in the holding tubes without the stopping and starting;and removing the fully coagulated egg from the holding tubes to form ascrambled egg product.
 16. A process as recited in claim 15 wherein thefirst heating heats the initially heated liquid egg product to atemperature of from about 130° F. to about 154° F. in about 1 to about25 minutes.
 17. A process as recited in claim 15 wherein the initiallyheated liquid egg product is further heated by injecting steam into theinitially heated liquid egg product.
 18. A process for producingscrambled egg product comprising: first heating a liquid egg product toa temperature less than a cooking temperature for the egg, but atemperature which is sufficiently high to prevent heat shock of theliquid egg product and prevent non-uniformity in the scrambled eggsproduced by the process to provide an initially heated liquid heated eggproduct; further heating the initially heated liquid egg product toprovide a homogeneously heated egg; the further heating to a temperatureeffective for cooking the egg and effective for causing the heatedliquid whole egg product to coagulate when the liquid egg product isheld in a holding tube; transporting the homogeneously heated liquid eggproduct to at least two holding tubes; holding the homogeneously heatedliquid egg product in the holding tubes for an amount of time effectivefor forming a fully coagulated egg; stopping and starting a flow of thehomogeneously heated liquid egg product in the holding tubes forproviding a discontinuous flow of the homogeneously heated liquid eggproduct in the holding tubes and effective to reduce laminar flow of thehomogeneously heated liquid egg product in the holding tubes compared toa laminar flow of the homogeneously heated liquid egg product whichwould develop in the holding tubes without the stopping and starting;and removing the cooked egg product to form scrambled egg product havinga homogeneous firmness throughout the egg product in the range of fromabout 20 mm to about 50 mm.
 19. A process as recited in claim 18 whereinthe first heating heats the initially heated liquid egg product to atemperature of from about 130° F. to about 154° F. in about 1 to about25 minutes.
 20. A process as recited in claim 18 wherein the initiallyheated liquid egg product is further heated by injecting steam into theinitially heated liquid egg product.
 21. A system for producingscrambled egg product, the system comprising: a holding tank effectivefor holding a liquid egg product at below a temperature of about 50° F.;a heat exchanger effective for heating the liquid egg product from theholding tank to a temperature in the range of from about 130° F. toabout 154° F. to provide an initially heated liquid egg product; a steaminjection device effective for injecting steam into the initially heatedliquid egg product and providing a steam heated liquid egg product, thesteam effective for heating the initially heated liquid egg product to acooking temperature; a holding tube which receives a flow of steamheated liquid egg product; and a means for controlling the flow of eggsto the holding tube, the means effective for stopping and starting theflow of steam heated liquid egg product to the holding tube, the holdingtube maintaining the steam heated egg product for a time and temperatureeffective for cooking the steam heated egg product.
 22. The system asrecited in claim 21 wherein the system further includes an extruderdownstream from the holding tubes for forming scrambled egg product. 23.The system as recited in claim 21, wherein the system provides thescrambled egg product with a homogeneous firmness of from about 20 mm toabout 50 mm.
 24. A process for producing scrambled egg productcomprising: first heating a liquid egg product to a temperature of fromabout 130° F. to about 154° F. to provide an initially heated liquid eggproduct having a viscosity of in the range of from about 100 cps toabout 1500 cps; injecting steam into the initially heated liquid eggproduct to provide a steam heated liquid egg-and to bring the initiallyheated liquid egg product to a temperature effective for causing theinitially heated egg product to coagulate when the liquid egg product isheld in a holding tube; transporting the steam heated egg product to atleast two holding tubes; holding the steam heated egg product in theholding tubes for an amount of time effective for forming a cooked eggproduct; stopping and starting a flow of the steam heated liquid eggproduct in the holding tubes, the stopping and starting effective forproviding a discontinuous flow of steam heated egg product in theholding tubes and effective to minimize a radial velocity gradient inthe flow of the steam heated egg in the holding tubes compared to aradial velocity gradient of steam heated egg which would develop in theholding tubes without the stopping and starting; and removing the cookedegg product to form scrambled egg product having a homogeneous firmnessthroughout the egg product in the range of from about 20 mm to about 50mm.